Opaque Pointer Types: GEP API migrations to specify the gep type explicitly

The changes to InstCombine (& SCEV) do seem a bit silly - it doesn't make
anything obviously better to have the caller access the pointers element
type (the thing I'm trying to remove) than the GEP itself, but it's a
helpful migration step. This will allow me to more obviously lock down
GEP (& Load, etc) API usage, then fix all the code that accesses pointer
element types except the places that need to be removed (most of the
InstCombines) anyway - at which point I'll need to just remove all that
code because it won't be meaningful anymore (there will be no pointer
types, so no bitcasts to combine)

SCEV looks like it'll need some restructuring - we'll have to do a bit
more work for GEP canonicalization, since it'll depend on how it's used
if we can even manage to canonicalize it to a non-ugly GEP. I guess we
can do some fun stuff like voting (do 2 out of 3 load from the GEP with
a certain type that gives a pretty GEP? Does every typed use of the GEP
use either a specific type or a generic type (i8*, etc)?)

llvm-svn: 233131

5 files changed, 15 insertions, 10 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 86fc0a411a5..a73ec9ecc02 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -374,7 +374,8 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
                                     PointerType *PTy,
                                     Type *Ty,
                                     Value *V) {
-  Type *ElTy = PTy->getElementType();
+  Type *OriginalElTy = PTy->getElementType();
+  Type *ElTy = OriginalElTy;
   SmallVector<Value *, 4> GepIndices;
   SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
   bool AnyNonZeroIndices = false;
@@ -558,7 +559,7 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
   Value *Casted = V;
   if (V->getType() != PTy)
     Casted = InsertNoopCastOfTo(Casted, PTy);
-  Value *GEP = Builder.CreateGEP(Casted,
+  Value *GEP = Builder.CreateGEP(OriginalElTy, Casted,
                                  GepIndices,
                                  "scevgep");
   Ops.push_back(SE.getUnknown(GEP));
diff --git a/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp b/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp
index 86d134baf5f..850c020edf3 100644
--- a/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp
+++ b/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp
@@ -343,6 +343,7 @@ Value *GenericToNVVM::remapConstantExpr(Module *M, Function *F, ConstantExpr *C,
     // GetElementPtrConstantExpr
     return cast<GEPOperator>(C)->isInBounds()
                ? Builder.CreateGEP(
+                     cast<GEPOperator>(C)->getSourceElementType(),
                      NewOperands[0],
                      makeArrayRef(&NewOperands[1], NumOperands - 1))
                : Builder.CreateInBoundsGEP(
diff --git a/llvm/lib/Target/R600/AMDGPUPromoteAlloca.cpp b/llvm/lib/Target/R600/AMDGPUPromoteAlloca.cpp
index ca9ea51e0fb..175dcd89e52 100644
--- a/llvm/lib/Target/R600/AMDGPUPromoteAlloca.cpp
+++ b/llvm/lib/Target/R600/AMDGPUPromoteAlloca.cpp
@@ -295,9 +295,9 @@ void AMDGPUPromoteAlloca::visitAlloca(AllocaInst &I) {
   DEBUG(dbgs() << "Promoting alloca to local memory\n");
   LocalMemAvailable -= AllocaSize;
 
+  Type *GVTy = ArrayType::get(I.getAllocatedType(), 256);
   GlobalVariable *GV = new GlobalVariable(
-      *Mod, ArrayType::get(I.getAllocatedType(), 256), false,
-      GlobalValue::ExternalLinkage, 0, I.getName(), 0,
+      *Mod, GVTy, false, GlobalValue::ExternalLinkage, 0, I.getName(), 0,
       GlobalVariable::NotThreadLocal, AMDGPUAS::LOCAL_ADDRESS);
 
   FunctionType *FTy = FunctionType::get(
@@ -333,7 +333,7 @@ void AMDGPUPromoteAlloca::visitAlloca(AllocaInst &I) {
   Indices.push_back(Constant::getNullValue(Type::getInt32Ty(Mod->getContext())));
   Indices.push_back(TID);
 
-  Value *Offset = Builder.CreateGEP(GV, Indices);
+  Value *Offset = Builder.CreateGEP(GVTy, GV, Indices);
   I.mutateType(Offset->getType());
   I.replaceAllUsesWith(Offset);
   I.eraseFromParent();
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 0625d8deca0..fe544c2f065 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1473,9 +1473,11 @@ Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
         // If we were able to index down into an element, create the GEP
         // and bitcast the result.  This eliminates one bitcast, potentially
         // two.
-        Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
-          Builder->CreateInBoundsGEP(OrigBase, NewIndices) :
-          Builder->CreateGEP(OrigBase, NewIndices);
+        Value *NGEP = cast<GEPOperator>(GEP)->isInBounds()
+                          ? Builder->CreateInBoundsGEP(OrigBase, NewIndices)
+                          : Builder->CreateGEP(
+                                OrigBase->getType()->getPointerElementType(),
+                                OrigBase, NewIndices);
         NGEP->takeName(GEP);
 
         if (isa<BitCastInst>(CI))
diff --git a/llvm/unittests/Linker/LinkModulesTest.cpp b/llvm/unittests/Linker/LinkModulesTest.cpp
index 91f97d76c9e..fbd03639fa7 100644
--- a/llvm/unittests/Linker/LinkModulesTest.cpp
+++ b/llvm/unittests/Linker/LinkModulesTest.cpp
@@ -35,7 +35,7 @@ protected:
     SwitchCase2BB = BasicBlock::Create(Ctx, "switch.case.2", F);
     ExitBB = BasicBlock::Create(Ctx, "exit", F);
 
-    ArrayType *AT = ArrayType::get(Type::getInt8PtrTy(Ctx), 3);
+    AT = ArrayType::get(Type::getInt8PtrTy(Ctx), 3);
 
     GV = new GlobalVariable(*M.get(), AT, false /*=isConstant*/,
                             GlobalValue::InternalLinkage, nullptr,"switch.bas");
@@ -61,6 +61,7 @@ protected:
   LLVMContext Ctx;
   std::unique_ptr<Module> M;
   Function *F;
+  ArrayType *AT;
   GlobalVariable *GV;
   BasicBlock *EntryBB;
   BasicBlock *SwitchCase1BB;
@@ -75,7 +76,7 @@ TEST_F(LinkModuleTest, BlockAddress) {
   GEPIndices.push_back(ConstantInt::get(Type::getInt32Ty(Ctx), 0));
   GEPIndices.push_back(F->arg_begin());
 
-  Value *GEP = Builder.CreateGEP(GV, GEPIndices, "switch.gep");
+  Value *GEP = Builder.CreateGEP(AT, GV, GEPIndices, "switch.gep");
   Value *Load = Builder.CreateLoad(GEP, "switch.load");
 
   Builder.CreateRet(Load);